Rat Bite Fever in Adults: Next-Line Management When Initial Intravenous Penicillin G Has Not Resolved Acute Symptoms Within 2 Days

This protocol addresses adults aged 18 years or older with rat bite fever (Streptobacillosis) who are not penicillin-allergic and whose initial course of intravenous penicillin G has not produced the expected clinical response within 2 days of starting treatment.

Clinical Scenario

Adult patient (age 18 or older) with rat bite fever, no penicillin allergy, currently on intravenous penicillin G at the standard initial dose. Acute symptoms have not rapidly resolved within the first 2 days of therapy, indicating that escalation is warranted.

Why Escalation Is Needed — Previous Treatment Line

The preceding line uses intravenous penicillin G at a standard starting dose range for a minimum of 7 days. The expected clinical goal is rapid resolution of acute symptoms, assessed within 2 days. When this response is not achieved at that point, escalation to this protocol applies.

Approach in This Protocol (Partial)

This protocol stays within the same antibiotic class as the initial line and involves an upward dose adjustment of intravenous penicillin G rather than a switch to a different agent. The precise escalation details and the complete regimen are available in the full protocol.

Instant Access to Structured Evidence-Based Regimens

References

DOI: 10.1128/CMR.00016-06

Adults with rat bite fever should receive 400,000 to 600,000 IU/day (240 to 360 mg) of intravenous penicillin G for at least 7 days, but this dose should be increased to 1.2 million IU/day (720 mg) if no response is seen within 2 days.

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